A machine tool in which a numerical control device is mounted performs machining by controlling each axis so that a tool moves to an instructed position and moving a movable unit. The numerical control device controls a movable range of the tool by setting a movable region, thereby avoiding interference between the tool and a working machine. A working machine provided with a rotary drive axis performs machining by adjusting the position and posture of the tool with driving the rotary drive axis to rotate. Conventionally, many measures have been taken on the numerical control device to narrow the movable region in view of the rotational angle of the rotary drive axis so as to avoid a tool tip from being brought into contact with the working machine.
Furthermore, there has been conventionally proposed a method of avoiding the interference with not narrowing a range of the movable region as much as possible by obtaining a position of a tool tip point from the length between a machine control point and the tool tip and a rotational angle of the tool and determining whether or not the tool falls within the range of the movable region (see, for example, Patent Literature 1).